Flat bed printing machine



Feb. 2, 1937. I. T. NELSON FLAT BED PRINTING MACHINE 2 Sheets-Sheet 1 Filed Nov. 22, 1934 Feb. 2, 1937. T. NELSON I FLAT BED PRINTING MACHINE 2 Sheets-Sheet 2 Filed NOV. 22, 1934 Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE Application November 22, 1934, Serial No. 754,354 In Great Britain November 6, 1934 1 Claim.

This invention relates to registering arrangements for the printing plates used in fiat bed printing machines and is a development of the invention forming the subject of United States Letters Patent No. 1,939,133, issued 12th December, 1933.

In the specification of the said Letters Patent there is described an arrangement comprising a flat bed presenting a surface formed with longitudinal guideways and adapted for the reception of printing plates deposited on said surface in rows transverse to said guideways series of plateengaging clamps interposed between adjacent rows of plates, said clamps being guided in said guideways for adjustment transversely of said rows of plates, and means for transmitting pressure in the longitudinal direction of said bed through the entire series of plates and their clamps in any given guideway whereby to lock said plates to the surface of said bed.

In the specification of United States Letters Patent No. 1,999,776, issued 30th April, 1935, there is described an arrangement of struts to be interposed between adjacent series of clamps, said struts being adapted to be pre-set to give the requisite inter-row spacing and being adjustable individually to effect independent adjustment of the plates after the entire series of plates and clamps have been locked up on the bed by the pressure-transmitting means. In this arrangement the clamps are formed with sunk recesses for reception of the struts.

The present invention provides an improved construction of the clamps with which may be associated adjustable struts as aforesaid to permit adjustment of the marginal spacing of the plates; alternatively non-adjustable marginal distance pieces may be adopted.

In practice, the clamps are each so formed that the clamp can be simply dropped into a guideway and then given a quarter turn to bring it into operative engagement with the guideway.

Further features will appear from the following description with reference to the accompanying drawings in which Fig. 1 is a plan View, Fig. 2 a fragmentary detail plan View drawn to a larger scale, Fig. 3 a section substantially on the line w-a' of Fig. 2, the printing plate being omitted, and Figs. 4 to 6 detail views, of a clamp arrange- 50 ment according to the present invention.

Referring to the drawings, I denotes printing plates which are interposed in rows between series of plate-engaging clamps 2.

The plates I are deposited upon a bed 3 which is reciprocated in the line T and which presents a plurality of parallel spaced guideways such as 4 extending longitudinally of the bed, i. e., parallel to the line of travel, T.

The clamps 2, which are freely slidable longitudinally of the bed, in engagement with the guideways 4, present undercut plate-engaging faces 8 which are preferably serrated so as securely to lock the plates I against lateral displacement.

In making ready, the plates I are deposited on the bed 3 in rows extending transversely of the guideways 4, each row of plates I being interposed between two series of clamps 2.

To space the clamps apart between the plate rows, there are interposed between corresponding clamps of adjacent series of clamps struts each including a screw-threaded spindle 35 engaged by a nut-forming member 36 and provided at one end with a collar 31 presenting sockets 38 engageable by a tommy bar or the like to effect rotation of the spindle 35. Beyond the collar 31 there is provided an unthreaded extension 35' of the spindle 35.

The clamps 2 are so contrived that they may be introduced into the guideways 4 at any point. For this purpose each clamp 2 is formed with a depending cylindrical neck 44 at the base of which are formed diametrally opposed shoulders 45 engageable under the shelves of a guideway 4. The neck 44 is provided with a transverse aperture 46 for free penetration by a strut spindle 35 or by the extension 35' thereof, and is slightly flattened to permit easy insertion of the clamp intothe guideways. As will readily be understood, the clamp is introduced into a guideway 4 with the clamp portion proper parallel with the guideway 4, and is then rotated through a right angle to bring its shoulders 45 into engagement with the shelves of the guideway 4, in which position the clamp is securely held against separation from the bed 3 while being slidably freely and angular ly movable within the guideway 4.

As will be understood, the arrangement is such that the individual printing plates I may be adjusted angularly within small limits as well as bodily, thus facilitating the operation of making ready for colour printing.

The struts 35 interposed between the pressure bars and the adjacent series of clamps 2 at the front and rear ends of the bed 3 are fitted with long nuts 36 and are unprovided with extensions 35.

4'! denotes one of a set of screw spindles arranged beneath the clamps and extending longitudinally of the bed 3. 48 and 49 denote transverse pressure plate sections of which the plate sections 48 have nuts engaged by the spindles 41, the spindles and pressure plate sections serving to transmit pressure through an entire series of plates and their clamps in any given guideway, whereby simultaneously to lock the plates to the bed.

I claim:

For a printing machine having a flat bed presenting undercut guideways, a plate-clamping device adapted to be interposed between a pair of spaced printing plates deposited on said bed transverse to said guideways, said plate-clamping device comprising a. pair of plate-engaging clamps each formed. with a depending cylindrical neck portion entering a guideway and of a diameter less than the width of said guideway, and diametrally opposed shoulders at the base of said neck portion, the extremities of said shoulders being spaced from one another a distance greater than the Width of that part of the guideway entered by said neck portion, said neck portions being formed with transverse apertures of circular cross-section, a strut spindle penetrating said apertures, said spindle provided with a fixed c01- lar affording an abutment for one of said clamps, and a nut-forming member threaded on said spindle and affording an abutment for the other of said clamps.

IAN THEODORE NELSON. 

